1. Field of the Invention
The invention relates to systems and methods for controlling a vehicle engine.
2. Background Discussion
An engine of an alternatively powered vehicle, e.g., a hybrid electric vehicle, may drive a compressor of the vehicle's air conditioning system such that when the engine is off during an electric drive mode, the compressor is off. The compressor may be selectively operated by starting the engine such that an occupant-selected desired temperature is achieved.
If a vehicle is not moving, the vehicle's engine may be stopped. The engine may be stopped, for example, if a cabin temperature is less than a threshold temperature. Such a strategy may result in the frequent stopping and starting of the engine which may affect fuel economy, driveability, and noise, vibration, and harshness. For example, the cabin temperature may be 1 degree Fahrenheit (F.) below a threshold temperature, resulting in an engine stop. An ambient temperature may be such that within a short period of time, e.g., five seconds, the cabin temperature would be greater than the threshold temperature, resulting in an engine start.
A system and method are desired that would prevent the frequent stopping and starting of a vehicle's engine.